An electrical feedthrough provides an electrical pathway between an interior of a hermetically-sealed housing of an electronics device to a point outside the housing. For example, an implantable medical device (IMD) may use one or more electrical feedthroughs to make electrical connections between electrical circuitry within the housing of the IMD and a lead, electrode, or sensor outside the housing. A feedthrough may comprise a ferrule that is mounted within an opening in the housing, a conductor that extends through the ferrule, and an insulating seal, which supports and electrically isolates the conductor from the ferrule.
Some IMDs include one feedthrough for each conductor exiting the IMD. As the electronics within the IMD are made smaller, the housing of the IMD may also be made smaller. In some implementations, the number of external leads, electrodes, or sensors that are coupled to an IMD has increased. In some cases, single-conductor feedthroughs are no longer used for some IMDs. Multi-conductor feedthroughs have been developed to provide hermetic pathways for a plurality of conductors (e.g., two or three or four or more) through the IMD housing. Some multi-conductor feedthroughs include a ceramic substrate mounted within a ferrule, and the ceramic substrate may include multiple conductive pathways formed in or through the ceramic substrate.